This invention relates generally as indicated to a fluid pressure actuator with stroke end lock mechanism, and more particularly, to such an actuator including a novel lock release mechanism for applying a substantially constant force to release the lock mechanism both before and after fluid pressure is applied to the actuator.
In certain actuator installations requiring a lock mechanism for locking the actuator against movement in one position, it is desirable to provide a lock release lever external to the actuator and isolate the lock release lever from the internal fluid pressure used to operate the actuator. The lock release lever may be powered by a lock piston which also admits fluid pressure to the actuator after the lock mechanism has been released to cause the actuator to move in the desired direction. However, this may have the objection that a larger differential area may be required on the lock piston to release the lock than would otherwise be required because of the fluid pressure in the actuator acting on the lock mechanism in opposition to the lock release force. Also, fluctuations in such fluid pressure could cause the lock piston to throttle back and thereby cause an undesirable reduction in the flow of fluid to the actuator during operation thereof.